Determining redundant radios

ABSTRACT

An algorithm for determining redundant radios in APs is disclosed. The algorithm first performs a coverage peak flattening algorithm to predict an impact to the total coverage area if a radio in a selected AP does not transmit signals in a frequency band. If the impact to the total coverage area is acceptable, the algorithm then performs a multi-point check algorithm to determine whether the radio in the selected AP is redundant in the frequency band. After determining that the radio in the selected AP is redundant in the frequency band, the algorithm transforms the redundant radio into various services based on the network deployment and user preference.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of provisional patent applicationSer. No. 62/333,599, filed May 9, 2016. The aforementioned relatedprovisional patent application is herein incorporated by reference inits entirety.

BACKGROUND

In order to deliver better Wi-Fi service and provide higher throughput,there is a significant increase in density of APs (access points) tocover large areas as compared to a few years ago.

While increasing the density of APs improves Wi-Fi availability andthroughput, it brings new challenges in densely populated deployments.For example, radios in multiple APs that are in close proximity maytransmit signals using the same channel of the same frequency band whichcan cause high co-channel interference between the radios. Highco-channel interference can negatively affect the performance of theradios in the APs.

SUMMARY

One embodiment of the present disclosure provides a device that includesa processor and a memory. The memory contains a program that, whenexecuted on the processor, performs an operation. The operationincludes, for an area covered by a plurality of access points operatingon a first channel in a frequency band, when a radio in a first accesspoint of the plurality of access points does not operate on the firstchannel in the frequency band, simulating whether the area covered by atleast one other radio in the plurality of access points satisfies apredetermined coverage threshold. The operation also includes, uponsimulating that the area covered by at least one other radio in theplurality of access points satisfies the predetermined coveragethreshold, determining that the radio in the first access point isredundant. The operation further includes, upon determining that theradio in the first access point is redundant, prohibiting the radio inthe first access point from operating on the first channel in thefrequency band.

One embodiment of the present disclosure provides a computer programproduct that includes a non-transitory computer-readable storage mediumhaving computer readable program code embodied therewith. For an areacovered by a plurality of access points operating on a first channel ina frequency band, when a radio in a first access point of the pluralityof access points does not operate on the first channel in the frequencyband, the computer readable program code simulates whether the areacovered by at least one other radio in the plurality of access pointssatisfies a predetermined coverage threshold. Upon simulating that thearea covered by at least one other radio in the plurality of accesspoints satisfies the predetermined coverage threshold, the computerreadable program code determines that the radio in the first accesspoint is redundant. Upon determining that the radio in the first accesspoint is redundant, the computer readable program code prohibits theradio in the first access point from operating on the first channel inthe frequency band.

One embodiment of the present disclosure provides a method. The methodincludes, for an area covered by a plurality of access points operatingon a first channel in a frequency band, when a radio in a first accesspoint of the plurality of access points does not operate on the firstchannel in the frequency band, simulating whether the area covered by atleast one other radio in the plurality of access points satisfies apredetermined coverage threshold. The method also includes, uponsimulating that the area covered by at least one other radio in theplurality of access points satisfies the predetermined coveragethreshold, determining that the radio in the first access point isredundant. The method further includes, upon determining that the radioin the first access point is redundant, prohibiting the radio in thefirst access point from operating on the first channel in the frequencyband.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a network controller controlling multiple APs in anetwork, according to one embodiment herein.

FIG. 2 illustrates a network controller, according to one embodimentherein.

FIG. 3 illustrates a method to determine redundant radios, according toone embodiment herein.

FIG. 4 illustrates a method to implement a coverage peak flatteningalgorithm, according to one embodiment herein.

FIG. 5 illustrates a square based model to approximate an area coveredby radios in a plurality of APs, according to one embodiment herein.

FIG. 6 illustrates an area covered by radios in a plurality of APs byusing the square based model, according to one embodiment herein.

FIG. 7 illustrates a visualized simulation of the coverage peakflattening algorithm, according to one embodiment herein.

FIG. 8 illustrates simulation results of the coverage peak flatteningalgorithm, according to one embodiment herein.

FIG. 9 illustrates a method to implement a multi-point check algorithm,according to one embodiment herein.

FIG. 10 illustrates a diagram of the multi-point check algorithm,according to one embodiment herein.

FIG. 11 illustrates a network controller controlling multiple radios tooperate in different modes, according to one embodiment herein.

DETAILED DESCRIPTION

One goal of Radio Resource Management (RRM) Transmit Power Controlalgorithms is to reduce co-channel interference without impacting theeffective coverage radius of a radio. However, in dense deployments suchas at enterprise sites, stadium venues or educational institutions, evenwith standard radio frequency (RF) planning and site surveys, the APstend to suffer from high co-channel interference. That is, multipleradios in multiple APs in close proximity may transmit signals using thesame channel of the same frequency band. Though the problem is usuallyseen with 2.4 GHz frequency band, radios using the 5 GHz frequency band(or other frequency bands) can also experience high co-channelinterference.

In some instances, a network engineer considers only the 5 GHz frequencyband when determining the number and the layout of the APs to providewireless access for a defined area. The 2.4 GHz frequency band isusually considered as secondary to the 5 GHz frequency band. Because ofthe lower frequency, wireless signals in the 2.4 GHz frequency band cantravel further than wireless signals in the 5 GHz frequency band. Thus,coverage determinations made for the 5 GHz frequency band are notdirectly applicable to the 2.4 GHz frequency band. Therefore, the 2.4GHz frequency band may be configured manually, e.g., a systemadministrator simply makes an educated guess on how many 2.4 GHz radiosare needed to provide sufficient coverage to the defined area. Toprevent contention and reduce co-channel interference between radios inmultiple APs in the 2.4 GHz frequency band, a system administrator maymanually power down some of the redundant 2.4 GHz radios. This manualmethod, however, can be cumbersome, tedious, and results in coverageholes. The present disclosure provides an algorithm that canautomatically determine redundant radios in APs without creatingcoverage holes.

FIG. 1 illustrates a network controller controlling a plurality of APsin a network, according to one embodiment herein. In FIG. 1, the networkcontroller 101 controls a plurality of APs from AP1 to AP5. In oneembodiment, each AP includes two radios where the first radio is adedicated 5 GHz radio that transmits signals in the 5 GHz frequency bandand the second radio is a XOR radio that can dynamically switch betweenthe 2.4 GHz and 5 GHz frequency bands. That is, the second radio cantransmit signals in either the 2.4 GHz frequency band or the 5 GHzfrequency band. The two radios in an AP can be active simultaneously onthe same frequency band or on different frequency bands. For example,the XOR radio and the dedicated 5 GHz radio in an AP can simultaneouslytransmit signals in the 5 GHz frequency band by using different channelsof the 5 GHz frequency band. In one embodiment, the network controller101 can be an AP, e.g., a master AP that can control other APs. Inanother embodiment, the network controller 101 can be a separatecomputing device. In another embodiment, the network controller 101 canbe a device in a cloud computing environment.

In one embodiment, the APs can offer various services based on thenetwork deployment and client density. For example, the AP1-AP5 have twooperation modes, i.e., a local working mode and a non-client servingrole. The operation modes apply to both radios of an AP. Also, theradios in AP1-AP5 have two radio roles, i.e., a dedicated radio role andan XOR radio role. In one embodiment, when operating in the localworking mode, the dedicated 5 GHz radio transmits signals in the 5 GHzfrequency band and the XOR radio transmits signals in either the 2.4 GHzfrequency band or the 5 GHz frequency band. In the non-client servingrole, however, the dedicated 5 GHz radio and the XOR radio do nottransmit signals in either the 5 GHz or the 2.4 GHz frequency bands.Also, in one embodiment, in the non-client serving role, the radiosconsume lower power than in the local working mode. In anotherembodiment, in the non-client serving role, the radios are passivemonitors that can receive signals transmitted on the 5 GHz or the 2.4GHz frequency bands but do not transmit signals.

In one embodiment, the network controller 101 determines whether a radioin an AP is redundant. That is, the network controller 101 determineswhether coverage area of the radio is already covered sufficiently(fully or almost fully) by at least one radio in a neighboring AP. Forexample, if AP1s XOR radio transmits signals using a channel of the 2.4GHz frequency band and if AP2 and AP3's XOR radios also transmit signalsusing the same channel of the 2.4 GHz frequency band which cover thesame area as AP1s XOR radio, then AP1s XOR radio is redundant. In thissituation, AP1s redundant XOR radio may cause co-channel interferencewith AP2 and AP3's XOR radios.

If the network controller 101 determines that a radio in an AP isredundant in a frequency band, the network controller 101 manages theredundant radio to mitigate co-channel interference in the frequencyband, e.g., the network controller 101 prohibits the redundant radiofrom transmitting signals in the frequency band. In one embodiment, thenetwork controller 101 instructs AP1s XOR radio to switch to the 5 GHzfrequency band. That is, the network controller 101 switches AP1s XORradio to transmit signals in the 5 GHz frequency band, so that AP1s XORradio does not transmit signals in the 2.4 GHz frequency band. Thus, theXOR radio of AP1 not only does not cause co-channel interference in the2.4 GHz frequency band but also increases capacity in the 5 GHzfrequency band. In another embodiment, the network controller 101instructs AP1s XOR radio to change from the local working mode to thenon-client serving role so that AP1s XOR radio does not transmit signalsin the 2.4 GHz frequency band and does not cause co-channel interferencein that band. In other embodiments, based on the network deployment anduser preference, the network controller 101 instructs AP1s XOR radio tochange from the local working mode to provide other services such asSenor Role for Wireless Service Assurance, Pre-emptive ChannelAvailability Check (CAC) for Zero-Touch Dynamic Frequency Selection(DFS) or to operate as Standby Radio for Client-Aware Hot-Standby mode.

FIG. 1 illustrates only one embodiment herein. In other embodiments, thenetwork controller 101 may control a different number of APs. Moreover,the APs may include a different number of radios. For example, the APsmay include a dedicated 5 GHz radio, a dedicated 2.4 GHz radio, and aXOR radio. In other embodiments, the radios of the APs may transmitsignals in frequency bands different from the 5 GHz frequency band andthe 2.4 GHz frequency band, as understood by an ordinary person in theart.

FIG. 2 illustrates the network controller 101, according to oneembodiment herein. The network controller 101 includes a processor 201and a memory 202. The processor 201 may be any computer processorcapable of performing the functions described herein. Although memory202 is shown as a single entity, memory 202 may include one or morememory devices having blocks of memory associated with physicaladdresses, such as random access memory (RAM), read only memory (ROM),flash memory or other types of volatile and/or non-volatile memory.

The memory 202 includes a radio resource management (RRM) component 203.The RRM component 203 provides a system level management of co-channelinterference, radio resources, and other radio transmissioncharacteristics in the network. The RRM component 203 includes corealgorithms for controlling parameters such as transmit power, userallocation, beamforming, data rates, handover criteria, modulationscheme, error coding scheme, etc. The RRM component 203 aims to utilizethe radio-frequency resources and radio network infrastructure in anefficient way.

In one embodiment, the RRM component 203 receives inter-radiomeasurement data reported from the APs controlled by the networkcontroller 101. The inter-radio measurement data may include but is notlimited to the channel frequency between two radios of different APs,transmit power, antenna information and the received signal strengthindicator (RSSI) or path loss between two radios of different APs.

In one embodiment, the RRM component 203 performs the inter-radiomeasurement based on a neighbor discovery protocol (NDP). By using NDP,each radio in each AP sends a broadcast message to all other radios inall other APs on all channels so that all other radios operating ondifferent channels can receive the broadcast message. The broadcastmessage may be a neighbor discovery packet with a predefined packetformat. When a radio in an AP receives the neighbor discovery packet, ituses the neighbor discovery packet to obtain the inter-radio measurementdata, and forwards the neighbor discovery packet and the inter-radiomeasurement data to the RRM component 203. Based on the receivedneighbor discovery packet and the inter-radio measurement data, the RRMcomponent 203 can understand how every radio using a channel hears everyother radio using the same channel and how every AP relates to other APsin the network controlled by the network controller 101.

The RRM component 203 includes a redundancy identification engine (RIE)204. Based on the measurement data received by the RRM component 203,the RIE 204 can identify redundant radios in APs in a frequency band.The RIE 204 includes a density value calculator 205, a radio frequency(RF) constellation calculator 206 and a redundancy determinator 207. Thedensity value calculator 205 identifies candidate APs for redundancydetermination, the RF constellation calculator 206 calculates relativelocations of neighboring APs, and the redundancy determinator 207determines whether a radio in an AP is redundant.

The redundancy determinator 207 includes a coverage peak flatteningsimulator 208 and a multi-point checker 209. The coverage peakflattening simulator 208 models a total coverage area covered by radiosin a plurality of APs and determines whether multiple radios arecovering an overlapping area of the total coverage area. The coveragepeak flattening simulator 208 also predicts an impact to the totalcoverage area if a radio in a selected AP does not transmit signals in afrequency band.

After the coverage peak flattening simulator 208 determines that theimpact to total coverage area is acceptable if the radio in the selectedAP does not transmit signals in a frequency band, the multi-pointchecker 209 further checks whether the radio is contributing to coverageareas of one or more radios in neighboring APs that are alreadydetermined as redundant. For example, if a radio in a neighboring APdoes not transmit signals in the frequency band because the radio in theneighboring AP was previously identified by the RIE 204 as redundant,the multi-point checker 209 checks whether the radio in the selected APis transmitting signals in the original coverage area (the coverage areabefore the redundant radio is prohibited from transmitting signals) ofthe redundant radio in the neighboring AP. If the coverage area of theradio in the selected AP does not overlap with the coverage areas of oneor more radios in neighboring APs that are already determined asredundant, the multi-point checker 209 further ensures that the coveragearea of the radio in the selected AP is sufficiently covered by one ormore radios in neighboring APs that are transmitting signals in thefrequency band. Algorithms implemented by the coverage peak flatteningsimulator 208 and the multi-point checker 209 will be described ingreater detail below.

When a radio in an AP is identified as redundant by the RIE 204, the RRMcomponent 203 manages the redundant radio in the AP to mitigateco-channel interference in a frequency band, e.g., the RRM component 203sends configuration messages to the AP either to switch the redundantradio to transmit signals in a different frequency band or change theradio into the non-client serving role. Thus, the redundant radio isprohibited from transmitting signals in the current frequency band or isprohibited from operating on its assigned channel to serve clients, sothat co-channel interference caused by the redundant radio is mitigated.

FIG. 3 illustrates a method 300 to determine redundant radios, accordingto one embodiment herein. At block 301, the density value calculator 205calculates, for each radio of a plurality of APs operating in afrequency band, a respective density value based on radios inneighboring APs that are within a threshold range of the radio, e.g,within a predefined distance from the radio. In one embodiment, radiosin the neighboring APs are in direct communication with the radio in thefrequency band, e.g., the 2.4 GHz frequency band. In one embodiment, theRRM component 203 uses NDP to calculate a respective density valueindicating respective neighboring APs that are in direct communicationwith a radio in an AP.

Using NDP, a radio in an AP sends a broadcast message to all otherradios in the neighboring APs using the frequency band. In oneembodiment, when a neighboring AP receives the neighbor discoverypacket, the neighboring AP forwards the neighbor discovery packet withinformation indicating that the neighbor discovery packet is directlyreceived from the sending AP to the RRM component 203. In this way, theRRM component 203 can identify the neighbors of the AP that sent thebroadcast message.

In one embodiment, after the neighboring APs are identified for each APcontrolled by the network controller 101, the density value calculator205 determines a density value for radios of the APs. Generally, thestronger neighbor relationship a radio has, the greater the densityvalue assigned to that radio. For example, the more neighbors a radiohas, the greater the density value assigned to that radio.

At block 302, the density value calculator 205 selects one or more APsfrom the plurality of APs based on the respective densities values. Inone embodiment, the density value calculator 205 selects the AP having aradio with the highest density value as the first candidate AP forredundancy determination. The second and the following candidate APs canbe selected similarly, as understood by an ordinary person in the art.

In other embodiments, the density value calculator 205 selects an APhaving a radio with the least load from the plurality of APs as thefirst candidate AP for redundancy determination. In other embodiments,the density value calculator 205 selects the AP having a radio with thehighest cumulative RSSI for the first n neighbors as the first candidateAP for redundancy determination.

At block 303, for each selected AP, the RF constellation calculator 206calculates locations of the selected AP's respective neighboring APsrelative to the selected AP. In one embodiment, the RF constellationcalculator 206 calculates locations of neighboring APs relative to theselected AP, based on the inter-radio measurement data such as the RSSIor path loss between two radios in different APs, as explained above.

In one embodiment, the RF constellation calculator 206 uses the inverseof the indoor Okumura-Hata model to derive estimated distances betweeneach pair of APs. Using this model, the RF constellation calculator 206can use the RSSI and/or path loss between two radios of each pair of APsto derive estimated distances between each pair of APs, as understood inthe art. After calculating the distances between each pair of APs,without loss of generality, the selected AP is placed on the origin andhas a coordinate of (0, 0). The RF constellation calculator 206calculates the relative location (e.g., coordinates) of each neighboringAP to the selected AP, based on the estimated distances between eachpair of APs, as understood in the art.

At block 304, the coverage peak flattening simulator 208 performs a peakcoverage flattening algorithm on radios in the selected APs to determineone or more radios that are potentially redundant in the frequency band.A radio in an AP is potentially redundant if the coverage peakflattening simulator 208 predicts that removing the radio does notaffect the total coverage area, thus the coverage area of the radio inthe AP is sufficiently covered by at least one radio of the AP'sneighboring APs. In one embodiment, the coverage peak flatteningsimulator 208 performs a peak coverage flattening algorithm on the XORradios in the selected APs to determine whether the XOR radios arepotentially redundant in the 2.4 GHz frequency band. The peak coverageflattening algorithm is described in detail later using FIGS. 4-8.

At block 305, once the coverage peak flattening simulator 208 hasprovided a list of potentially redundant radios, the multi-point checker209 then performs the multi-point check algorithm on the potentiallyredundant radios. For each potentially redundant radio, at block 305,the multi-point checker 209 further checks whether the radio has acoverage area that overlaps with coverage areas of radios in neighboringAPs that were already determined as redundant. If not, at block 305, themulti-point checker 209 further ensures that the coverage area of theradio in the selected AP is sufficiently covered by one or more radiosin neighboring APs. In other words, after the coverage peak flatteningsimulator 208 predicts that the coverage area of the radio in theselected AP is sufficiently covered by at least one radio of itsneighboring APs and the radio is potentially redundant, the multi-pointchecker 209 verifies whether the prediction made by the coverage peakflattening simulator 208 is correct. The multi-point check algorithm isdescribed in detail later using FIGS. 9-10.

At block 306, the multi-point checker 209 determines whether the radiosare actually redundant. If the answer is “NO” at block 306. The method300 proceeds to block 307. At block 307, the RRM component 203 does notprohibit the potentially redundant radios identified at block 304 fromtransmitting signals in the frequency band since these radios are notredundant—i.e., their coverage areas are not sufficiently covered byradios in neighboring APs.

On the other hand, if the answer is “YES” at block 306, the method 300proceeds to block 308. At block 308, the RRM component 203 prohibits theredundant radio in the selected AP from transmitting signals in thefrequency band.

In one embodiment, in order to prohibit the redundant radio in theselected AP from transmitting signals in the frequency band, either theredundant radio is switched to transmit signals in a different frequencyband or the redundant radio is changed to the non-client serving role.Specifically, once a radio in an AP is identified as redundant by theRIE 204, the RRM component 203 sends configuration messages to the APeither to switch the redundant radio to transmit signals in a differentfrequency band or change the radio into a non-client serving role.

For example, if an XOR radio of an AP that is transmitting signals inthe 2.4 GHz frequency band is determined as a redundant radio, the RRMcomponent 203 can either switch the XOR radio to transmit signals in the5 GHz frequency band or change the XOR radio into the non-client servingrole depending on the users' requirements or the usages of the network.For example, the RRM component 203 can switch the XOR radio to transmitsignals in the 5 GHz frequency band to serve more users in the 5 GHzfrequency band, or the RRM component 203 can change the XOR radio intothe non-client serving role. Because the redundant XOR radio is nolonger transmitting signals in the 2.4 GHz frequency band, the redundantXOR radio does not cause co-channel interference in the 2.4 GHzfrequency band.

In one embodiment, when users in the 2.4 GHz frequency band areassociated with a weaker RSSI to a nearby AP or in case that aneighboring 2.4 GHz radio does not work properly, the RRM component 203can revert the XOR radio back to the 2.4 GHz frequency band to transmitsignals in the 2.4 GHz frequency band to avoid coverage holes in the 2.4GHz frequency band. When the XOR radio is reverted back to the 2.4 GHzfrequency band, the XOR radio will be ignored in future redundancyidentification for a time period, e.g., the next 60 minutes.

After the RRM component 203 prohibits the redundant radio fromtransmitting signals in the frequency band or prohibits the redundantradio from operating on its assigned channel to serve clients, at block309, the RRM component 203 dynamically transfers the radio to operate ina suitable operation mode, based on the users' requirements and/or thenetwork conditions.

In one embodiment, when RIE 204 of the network controller 101 identifiesone or more redundant radios, RRM 203 of the network controller 101utilizes channel, power and client optimization algorithms to evaluateRF conditions, available channel sets and client density in order todetermine how to operate the redundant radios.

FIG. 4 illustrates a method 400 to implement the coverage peakflattening algorithm described at block 304 of the method 300, accordingto one embodiment herein. At block 401, the coverage peak flatteningsimulator 208 models a total coverage area covered by the plurality ofAPs transmitting signals in the frequency band. The method 400 isdescribed in parallel with FIGS. 5-8.

FIG. 5 shows a square based model of the total coverage area, accordingto one embodiment herein. As shown in FIG. 5, the circle 501 with aradius R indicates an actual total coverage area covered by an AP. Thesize of the actual total coverage area is π*R². While modeling theactual total coverage area by using the circle 501 provides an accuratemodel, doing so introduces intensive computational complexity whendetermining overlapping coverage areas of multiple APs inside the circle501. Thus, in order to reduce the computational complexity, the coveragepeak flattening simulator 208 models the actual total coverage areausing a square based model which also provides a sufficiently accuratemodel.

In one embodiment, at block 401, the coverage peak flattening simulator208 models the actual total coverage area using a square based model toapproximate the actual total coverage area inside the circle 501. Forexample, there are three candidate square based models. The areaindicated by the square 502 is the first candidate square based model.The side length of the square 502 is √{square root over (2)}*R and thesize inside the square 502 is 2*R². The area indicated by the square 503is the second candidate square based model. The side length of thesquare 502 is 2*R and the size inside the square 502 is 4*R². The areaindicated by the square 504 (using dotted lines) is the third candidatesquare based model. The side length of the square 502 is (1+1/√{squareroot over (2)})R and the size inside the square 502 is (1.5+√{squareroot over (2)})R². Among the three square based models, the size insidethe third square based model, i.e., (1.5+√{square root over (2)})R², isthe closest to the size of the actual total coverage area, i.e., π*R².Thus, the coverage peak flattening simulator 208 uses the third squarebased model inside the square 504 to approximate the actual totalcoverage area inside the circle 501. In other embodiments, the coveragepeak flattening simulator 208 can use the first or the second squarebased models depending on the requirement of the accuracy to approximatethe actual total coverage area.

FIG. 6 illustrates the total coverage area by using the third squarebased model, according to one embodiment herein. In FIG. 6, the totalcoverage area is a 60 meter×60 meter square area. The 60 meter×60 metersquare area is split into a plurality of grids. Each grid indicates asub-area that is covered by one or more radios in the APs. The gridsthat are covered by multiple radios are considered as overlappingcoverage areas. In one embodiment as shown in FIG. 6, the grid with alighter color or shading is covered by a higher number of radios thanthe grid with a darker color or shading. For example, the grid indicatedby arrow 601 is covered by 5 radios while the grid indicated by arrow602 is covered by 2 radios.

Returning to method 400, at block 402, the coverage peak flatteningsimulator 208 simulates the impact to the total coverage area when theradio in the selected AP does not transmit signals in the frequencyband. If the total coverage area satisfies a pre-defined coveragethreshold, even after prohibiting the radio in the selected AP fromtransmitting signals in the frequency band then the coverage peakflattening simulator 208 predicts that the coverage area of the radio inthe selected AP is sufficiently covered by at least one radio of itsneighboring APs. On the other hand, if the radio in the selected AP isprohibited from transmitting signals in the frequency band and the totalcoverage area does not satisfy the pre-defined coverage threshold, thecoverage peak flattening simulator 208 predicts that the coverage areaof the radio in the selected AP is not sufficiently covered by at leastone of its neighboring APs.

FIG. 7 illustrates a visualized simulation of the coverage peakflattening algorithm, according to one embodiment herein. In thesimulations, the total coverage area is the 60 meter×60 meter squarearea as shown in FIG. 6. As shown in FIG. 7, a grid in the 60 meter×60meter area is denoted by its coordinates in X axis and Y axis, andnumber of APs that cover the gird in a frequency band is denoted by itscoordinate in Z axis. For example, 701 denotes a grid at (20, 10) whichis covered by 6 APs in a frequency band, e.g., there are six radios insix APs that are transmitting signals in the 2.4 GHz frequency band.Thus, the coordinate at 701 is (20, 10, 6). Similarly, 702 denotes agrid at (30, 10) which is covered by 5 APs in the frequency band. Thus,the coordinate at 702 is (30, 10, 5). Also, 703 denotes a grid at (50,50) which is not covered by any AP in the frequency band. Thus, thecoordinate at 703 is (50, 50, 0). The total coverage area is reducedwhenever one of the coordinates which was previously covered by at leastone AP is no longer covered by any AP in the simulation.

In one embodiment, the simulation of coverage peak flattening algorithmstarts from the highest peak 701 in the simulation and an AP that coversgrid 701 which has the highest density value. In another example, thesimulation of coverage peak flattening algorithm may select an AP thatcovers grid 701 and has the least load among the 6 APs that cover grid701. In the simulation, the radio in the selected AP that covers grid701 is prohibited from transmitting signals in the frequency band or isprohibited from operating on its assigned channel to serve clients. Forexample, the XOR radio in the selected AP that covers grid 701 isprohibited from transmitting signals in the 2.4 GHz frequency band. Thesimulation results determine whether the total coverage area is changed.

Once the simulation for the selected AP is finished, at block 403, thecoverage peak flattening simulator 208 determines whether the impact tothe total coverage area is acceptable. In one embodiment, if the totalcoverage area satisfies the coverage threshold, the impact to the totalcoverage area is considered as acceptable. Otherwise, the impact to thetotal coverage area is considered as not acceptable. For example, thecoverage threshold can be a tolerance factor T, which indicates that thecurrent total coverage area after prohibiting the radio in the selectedAP from transmitting signals in the frequency band is τ%, e.g., 90%, ofthe geographic area of the original total coverage area beforeprohibiting the radio in the selected AP from transmitting signals inthe frequency band. After prohibiting the radio in the selected AP fromtransmitting signals in the frequency band, the current coverage area isthe area covered by at least one radio in one of the APs that arecontinuing to transmit signals in the frequency band.

If the impact to the total coverage area is not acceptable at block 403,e.g., the current total coverage area is below τ% of the original totalcoverage area, the method 400 proceeds to block 405 where the coveragepeak flattening simulator 208 determines that radio in the selected APis not potentially redundant in the frequency band. In one embodiment,the AP with the highest density value does not have a redundant radio,the coverage peak flattening simulator 208 continues to select anotherAP.

On the other hand, if the impact to the total coverage area isacceptable, e.g., the current total coverage area is at least τ% of theoriginal total coverage area, at block 404, the coverage peak flatteningsimulator 208 determines that the radio in the selected AP ispotentially redundant in the frequency band. For example, if the impactto the total coverage area is acceptable, the radio in the selected APthat covers grid 701 is determined as potentially redundant and removedfrom the simulation. That is, after one simulation, the coordinate at701 is changed from (20, 10, 6) to (20, 10, 5).

In one embodiment, the coverage peak flattening algorithm can beimplemented recursively. As shown in FIG. 4, after determining whetherthe radio in the selected AP is potentially redundant at block 404 or405, the method 400 proceeds to block 406. At block 406, the coveragepeak flattening simulator 208 selects the next candidate AP. In oneembodiment, the coverage peak flattening simulator 208 selects thecandidate AP with the second highest density value (peak).

At block 407, the coverage peak flattening simulator 208 determineswhether the next candidate AP is found. If the answer at block 407 is“Yes”, then the method 400 in FIG. 4 returns to block 402 to implementthe coverage peak flattening algorithm for the next candidate AP and soon. If the answer at block 407 is “No”, the method 400 proceeds to block408 to finish the simulation.

In one embodiment, the simulation runs recursively until the impact tothe total coverage area is not acceptable. In each iteration of thesimulation, a radio in a selected AP that covers a grid in the 60meter×60 meter area is prohibited from transmitting signals in afrequency band or is prohibited from operating on its assigned channelto serve clients. When the coverage peak flattening algorithm isimplemented multiple times until the impact to the total coverage areais not acceptable, e.g., until the coverage threshold is reached,multiple APs may be determined as potentially redundant and are removedfrom the simulation. Accordingly, the coordinates at different grids maybe changed when the simulation is ended.

FIG. 8 illustrates the simulation results of the coverage peakflattening algorithm, according to one embodiment herein. As shown inFIG. 8, when the simulation is implemented multiple times until thecoverage threshold is reached, the coordinate at 701 is (20, 10, 3),which indicates that 3 APs cover grid 701 while satisfying theacceptable total coverage area, i.e., 3 APs among the original 6 APsthat cover grid 701 are determined as potentially redundant. Also, whenthe simulation is implemented multiple times until the threshold isreached, the coordinate at 702 is (30, 10, 3) which indicates that 3 APscover grid 702 while satisfying the acceptable total coverage area,i.e., 2 APs among the original 5 APs that cover grid 702 are determinedas potentially redundant. Thus, the number of APs that cover a same gridin the 60 meter×60 meter area is reduced, i.e., the density value (peak)is flattened. Using the coverage peak flattening algorithm recursively,the coverage peak flattening simulator 208 can determine which APsinclude potentially redundant radios based on the simulation results.

FIGS. 4-8 only show one embodiment herein. In another embodiment, aseparate computing system can model the area and performs thesimulation. The separate computing system can transmit the simulationresults to the network controller 101 to determine whether the selectedAP has a redundant radio in the frequency band.

FIG. 9 illustrates a method 900 for performing the multi-point checkalgorithm as described at block 307 of the method 300, according to oneembodiment herein. At block 901, the multi-point checker 209 selects aset of points distributed within a coverage area of the radio in theselected AP.

In one embodiment, at block 901, the multi-point checker 209 selects aset of 13 points. FIG. 10 illustrates the multi-point check algorithmusing a 13-point distribution (including the origin), according to oneembodiment herein. As shown, the selected AP 1001 is located at theorigin with the coordinate (0, 0) and another three neighboring APs 1002are located nearby. A coverage circle 1003 indicates the coverage areaof the radio (e.g., the XOR radio) in the selected AP 1001 in thefrequency band (e.g., the 2.4 GHz frequency band). Similarly, the threecoverage circles for the neighboring APs 1002 are denoted as 1005, whichindicate the coverage areas of the radios in the three neighboring APsin the same frequency band. The multi-point checker 209 selects theorigin and also selects another 12 points in the coverage circle 1003.This includes 8 points uniformly distributed on the coverage circle 1003and another 4 points uniformly distributed inside the coverage circle1003. For simplicity of illustration, only two of the 12 points aredenoted as 1004.

Once the set of points is selected, at block 902, the multi-pointchecker 209 determines coordinates of each of the set of points. In FIG.10, the multi-point checker 209 determines the coordinates of each ofthe 12 points 1004 relative to the origin (the origin's coordinate isknown as (0,0)). The multi-point checker 209 calculates the coordinatesof each of the 12 points 1004 relative to the origin based on thedistances of each of the 12 points 1004 relative to the origin and theuniform distribution of the 12 points. For example, the coordinates ofthe 8 points uniformly distributed on the coverage circle 1003 can be(0, r),

$\left( {{\frac{1}{\sqrt{2}}r},{\frac{1}{\sqrt{2}}r}} \right),$

(r, 0),

$\left( {{\frac{1}{\sqrt{2}}r},{{- \frac{1}{\sqrt{2}}}r}} \right),$

(0, −r),

$\left( {{{- \frac{1}{\sqrt{2}}}r},{{- \frac{1}{\sqrt{2}}}r}} \right),$

(−r, 0),

$\left( {{{- \frac{1}{\sqrt{2}}}r},{\frac{1}{\sqrt{2}}r}} \right),$

and the coordinates of the 4 points uniformly distributed inside thecoverage circle 1003 can be

$\left( {{\frac{1}{2}r},{\frac{1}{2}r}} \right),\left( {{\frac{1}{2}r},{{- \frac{1}{2}}r}} \right),\left( {{{- \frac{1}{2}}r},{{- \frac{1}{2}}r}} \right),\left( {{\frac{1}{2}r},{{- \frac{1}{2}}r}} \right),$

where r is the radius of the selected AP 1001's coverage circle 1003,denoted as 1007.

Returning to the method 900, at block 903, the multi-point checker 209calculates RF distances between each neighboring AP of the selected APand each of the set of points. In one embodiment, RF distances refer todistances that are computed solely based on the measured path lossbetween APs. RF distances do not necessarily correspond to the physicallocation distances. For example, the presence of a wall between two APswill cause a further RF distance between the two APs than the physicaldistance. In some embodiments of the present disclosure, using RFdistances is preferred to using the physical distances.

As shown in FIG. 10, the multi-point checker 209 calculates thedistances between each neighboring AP 1002 and each of the 13 points(the 12 points 1004 and the origin), based on the coordinates of eachneighboring AP 1002 and the coordinates of each of the 13 points. In oneembodiment, the RF constellation calculator 206 calculates thecoordinates of each neighboring AP 1002 relative to the origin asdescribed above. For each of the three neighboring APs 1002, themulti-point checker 209 calculates the distances between the neighboringAP 1002 and each of the 13 points.

Once distances between each neighboring AP of the selected AP and eachof the set of points are calculated, at block 904, the multi-pointchecker 209 compares the distance between a point and a neighboring APwith that neighboring AP's coverage radius in the frequency band. Asshown in FIG. 10, the multi-point checker 209 compares the distancebetween a point 1004 and a neighboring AP 1002 with that neighboring AP1002's coverage radius in the frequency band. A neighboring AP 1002'scoverage radius is the radius of that neighboring AP 1002's coveragecircle 1005, denoted as 1006.

Based on the comparisons in block 904, at block 905, the multi-pointchecker 209 determines whether the radio in the selected AP iscontributing to coverage areas of one or more radios in neighboring APsthat are already determined as redundant. In one embodiment, if a radioin a neighboring AP is already marked as redundant, the multi-pointchecker 209 determines whether one or more points of the set of pointsare inside the coverage area of the redundant radio in the neighboringAP. If so, the radio in the selected AP contributes to the coverage areaof the redundant radio in neighboring APs (“YES” at block 905). Forexample, it is assumed that the radio in the leftmost neighboring AP1002 was previously determined as redundant and does not transmitsignals. The multi-point checker 209 determines whether one or morepoints of the set of points 1004 are inside the leftmost circle 1005(the original coverage area of the leftmost neighboring AP 1002 beforeit is prohibited from transmitting signals). As shown in FIG. 10, thereare 6 points 1004 inside the leftmost circle 1005, thus, the multi-pointchecker 209 determines that the radio 1001 is contributing to thecoverage area of the redundant radio in the leftmost neighboring AP1002. Then the method 900 proceeds to block 908. At block 908, themulti-point checker 209 determines that the radio in the selected AP isnot redundant in the frequency band. In this way, the multi-pointchecker 209 avoids potential coverage holes, e.g., one or more radioscovering the same area are determined as redundant such that there aresome areas previously covered are not covered anymore.

In one embedment, at block 905, the multi-point checker 209 alsoidentifies which neighboring AP includes which of the set of points inthe neighboring AP's coverage area. In this way, the multi-point checker209 identifies the one or more neighboring APs that contribute coverageto the coverage area of the radio in the selected AP.

If the answer at block 905 is “NO”, the method proceeds to block 906. Atblock 906, the multi-point checker 209 determines whether a pre-definednumber of points of the set of points are inside at least oneneighboring AP's coverage area in the frequency band. Referring to FIG.10, if the distance between a point 1004 and a neighboring AP 1002 isless than the coverage radius 1006 of that neighboring AP 1002 in thefrequency band, the multi-point checker 209 determines that the point1004 is inside the coverage area of that neighboring AP 1002 in thefrequency band. In this way, the multi-point checker 209 determineswhether a pre-defined number of the 13 points are inside one or moreneighboring APs 1002's coverage area in the frequency band.

In one embodiment, the multi-point checker 209 determines whether allthe points of the set of points are inside at least one neighboring AP'scoverage area in the frequency band. In another embodiment, themulti-point checker 209 determines whether a certain number (not all) ofpoints of the set of points are inside at least one neighboring AP'scoverage area in the frequency band. That is, the multi-point checker209 checks all the points and can nonetheless determine whether athreshold number (but not all) of the set of points are inside aneighboring AP's coverage area in the frequency band. In anotherembodiment, the multi-point checker 209 uses a coverage overlap factor(COF) to indicate how well the circle is covered, e.g., fully covered oralmost fully covered. In one embodiment, the COF is defined as:(percentage of points in circle fully covered)+α×(percentage of pointsin circle covered with an additional margin based on their proximity tothe origin), where a is a coefficient and 0<α<1.

If the answer at block 906 is “YES”, at block 907, the multi-pointchecker 209 determines that the radio in the selected AP is redundant inthe frequency band, i.e., the selected candidate AP has a redundantradio in the frequency band. For example, as shown in FIG. 10, all the13 points 1004 are inside the coverage circle 1005 of at least oneneighboring AP 1002. The coverage area of the selected AP 1001 in thefrequency band is considered as sufficiently covered by one or more ofits neighboring APs 1002. Thus, the radio in the selected AP 1001transmitting signals in the frequency band is determined as redundant inthe frequency band.

If the answer at block 906 is “NO”, at block 908, the multi-pointchecker 209 determines that the radio in the selected AP is notredundant in the frequency band. For example, if a pre-defined number ofthe 13 points in FIG. 10 are not inside at least one neighboring AP1002's coverage circle 1005, the selected AP 1001's coverage area in thefrequency band is not considered as sufficiently covered by one or moreof its neighboring APs 1002. Thus, the multi-point checker 209determines that the radio in the selected AP 1001 is not redundant inthe frequency band.

In one embodiment, after determining whether the radio in the selectedAP is redundant, the multi-point checker 209 implements the multi-pointcheck algorithm to determine whether the next candidate AP has aredundant radio and so on. For example, after the coverage peakflattening simulator 208 performs the coverage peak flattening algorithmrecursively, the coverage peak flattening simulator 208 can provide alist of potentially redundant radios to the multi-point checker 209. Themulti-point checker 209 can perform the multi-point check algorithm oneach radio in the list, as understood by an ordinary person in the art.

FIG. 10 only illustrates one embodiment of the multi-point checkalgorithm. In other embodiments, a different number of points may beused. In other embodiments, the multiple points may be distributed atdifferent locations on or inside the selected AP's coverage circle. Inother embodiments, the coverage circles may indicate different coverageareas, e.g., the XOR radios' coverage area in the 5 GHz frequency band.

FIG. 11 illustrates that the network controller 101 controls multipleredundant XOR radios in 2.4 GHz frequency band to operate in differentoperation modes, according to one embodiment herein. In FIG. 11, the XORradios in AP1-AP5 are determined as redundant radios in 2.4 GHzfrequency band. RRM 203 of the network controller 101 sends differentconfiguration messages to different redundant XOR radios to instruct theredundant XOR radios to operate in different modes. For examples, theXOR radio in AP1 is switched to transmit signals in 5 GHz frequency banddue to high client density in 5 GHz frequency band. The XOR radio in AP2is changed to the non-client serving role to perform security andnetwork monitoring. The XOR radio in AP3 is operated as a spectrumsensor to provide wireless service assurance service. The XOR radio inAP4 is operated to provide Channel Availability Check (CAC) forZero-Touch Dynamic Frequency Selection (DFS) service. The XOR radio inAP5 is operated as Client-Aware high availability (HA) Radio in ahot-standby mode. In other embodiments, the network controller 101 cancontrol the redundant XOR radios to operate in other modes, asunderstood by an ordinary person in the art. Thus, the networkcontroller 101 can dynamic configure redundant XOR radios based onevaluations of RF conditions, available channel sets and client densityin the network.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

In the preceding, reference is made to embodiments presented in thisdisclosure. However, the scope of the present disclosure is not limitedto specific described embodiments. Instead, any combination of thefollowing features and elements, whether related to differentembodiments or not, is contemplated to implement and practicecontemplated embodiments. Furthermore, although embodiments disclosedherein may achieve advantages over other possible solutions or over theprior art, whether or not a particular advantage is achieved by a givenembodiment is not limiting of the scope of the present disclosure. Thus,the following aspects, features, embodiments and advantages are merelyillustrative and are not considered elements or limitations of theappended claims except where explicitly recited in a claim(s). Likewise,reference to “the invention” shall not be construed as a generalizationof any inventive subject matter disclosed herein and shall not beconsidered to be an element or limitation of the appended claims exceptwhere explicitly recited in a claim(s).

Aspects of the present invention may take the form of an entirelyhardware embodiment, an entirely software embodiment (includingfirmware, resident software, micro-code, etc.) or an embodimentcombining software and hardware aspects that may all generally bereferred to herein as a “circuit,” “module” or “system.”

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. A device, comprising: a processor; a memorycontaining a program that, when executed on the computer processor,performs an operation, the operation comprising: for an area covered bya plurality of access points operating on a first channel in a frequencyband: when a radio in a first access point of the plurality of accesspoints does not operate on the first channel in the frequency band,simulating whether the area covered by at least one other radio in theplurality of access points satisfies a predetermined coverage threshold;upon simulating that the area covered by at least one other radio in theplurality of access points satisfies the predetermined coveragethreshold, determining that the radio in the first access point isredundant; and upon determining that the radio in the first access pointis redundant, prohibiting the radio in the first access point fromoperating on the first channel in the frequency band.
 2. The device ofclaim 1, wherein determining that the radio in the first access point isredundant comprises: selecting a set of points distributed within acoverage area of the radio in the first access point; calculatingdistances between each of a plurality of neighboring access points ofthe first access point and each of the set of points, wherein theplurality of neighboring access points are in direct communication withthe radio in the first access point; and determining that a pre-definednumber of the set of points are inside the coverage area of at least oneof the neighboring access points based on the calculated distances. 3.The device of claim 2, wherein determining that the radio in the firstaccess point is redundant comprises: determining that the radio in thefirst access point is not contributing to coverage areas of one or moreradios in the neighboring access points that are already determined asredundant.
 4. The device of claim 2, wherein determining that the radioin the first access point is redundant comprises: identifying one ormore radios in the neighboring access points that contribute coverage tothe coverage area of the radio in the first access point.
 5. The deviceof claim 1, wherein the radio in the first access point comprises a XORradio configured to dynamically switch between the frequency band and adifferent frequency band.
 6. The device of claim 1, wherein thepredetermined coverage threshold comprises a percentage of the size ofthe area.
 7. The network controller of claim 1, the operation furthercomprising: when a radio in a second access point of the plurality ofaccess points does not operate on the first channel in the frequencyband, simulating whether the area covered by at least one other radio inthe plurality of access points satisfies the predetermined coveragethreshold; upon simulating that the area covered by at least one otherradio in the plurality of access points does not satisfy thepredetermined coverage threshold, determining that the radio in thesecond access point is not redundant.
 8. A computer program product,comprising: a non-transitory computer-readable storage medium havingcomputer readable program code embodied therewith, wherein the computerreadable program code is configured to: for an area covered by aplurality of access points operating on a first channel in a frequencyband: when a radio in a first access point of the plurality of accesspoints does not operate on the first channel in the frequency band,simulate whether the area covered by at least one other radio in theplurality of access points satisfies a predetermined coverage threshold;upon simulating that the area covered by at least one other radio in theplurality of access points satisfies the predetermined coveragethreshold, determine that the radio in the first access point isredundant; and upon determining that the radio in the first access pointis redundant, prohibit the radio in the first access point fromoperating on the first channel in the frequency band.
 9. The computerprogram product of claim 8, wherein the computer readable program codeis further configured to: select a set of points distributed within acoverage area of the radio in the first access point; calculatedistances between each of a plurality of neighboring access points ofthe first access point and each of the set of points, wherein theplurality of neighboring access points are in direct communication withthe first access point; and determine that a pre-defined number of theset of points are inside the coverage area of at least one of theneighboring access points based on the calculated distances.
 10. Thecomputer program product of claim 9, wherein the computer readableprogram code is further configured to: determine that the radio in thefirst access point is not contributing to coverage areas of one or moreradios in the neighboring access points that are already determined asredundant.
 11. The computer program product of claim 9, wherein thecomputer readable program code is further configured to: identify one ormore radios in the neighboring access points that contribute coverage tothe coverage area of the radio in the first access point.
 12. Thecomputer program product of claim 8, wherein the radio in the firstaccess point comprises a XOR radio configured to dynamically switchbetween the frequency band and a different frequency band.
 13. Thecomputer program product of claim 8, wherein the predetermined coveragethreshold comprises a percentage of the size of the area.
 14. Thecomputer program product of claim 8, wherein the computer readableprogram code is further configured to: when a radio in a second accesspoint of the plurality of access points does not operate on the firstchannel in the frequency band, simulate whether the area covered by atleast one other radio in the plurality of access points satisfies thepredetermined coverage threshold; upon simulating that the area coveredby at least one other radio in the plurality of access points does notsatisfy the predetermined coverage threshold, determine that the radioin the second access point is not redundant.
 15. A method, comprising:for an area covered by a plurality of access points operating on a firstchannel in a frequency band: when a radio in a first access point of theplurality of access points does not operate on the first channel in thefrequency band, simulating whether the area covered by at least oneother radio in the plurality of access points satisfies a predeterminedcoverage threshold; upon simulating that the area covered by at leastone other radio in the plurality of access points satisfies thepredetermined coverage threshold, determining that the radio in thefirst access point is redundant; and upon determining that the radio inthe first access point is redundant, prohibiting the radio in the firstaccess point from operating on the first channel in the frequency band.16. The method of claim 15, wherein determining that the radio in thefirst access point is redundant comprises: selecting a set of pointsdistributed within a coverage area of the radio in the first accesspoint; calculating distances between each of a plurality of neighboringaccess points of the first access point and each of the set of points,wherein the plurality of neighboring access points are in directcommunication with the first access point; and determining that apre-defined number of the set of points are inside the coverage area ofat least one of the neighboring access points based on the calculateddistances.
 17. The method of claim 16, wherein determining that theradio in the first access point is redundant comprises: determining thatthe radio in the first access point is not contributing to coverageareas of one or more radios in the neighboring access points that arealready determined as redundant.
 18. The method of claim 16, whereindetermining that the radio in the first access point is redundantcomprises: identifying one or more radios in the neighboring accesspoints that contribute coverage to the coverage area of the radio in thefirst access point.
 19. The method of claim 15, wherein the radio in thefirst access point comprises a XOR radio configured to dynamicallyswitch between the frequency band and a different frequency band. 20.The method of claim 15, wherein the predetermined coverage thresholdcomprises a percentage of the size of the area.